vodka vs John Barleycorn

vodka and John Barleycorn both are nouns.

Word	Noun	Adjective	Verb	Adverb
vodka	Yes	No	No	No
John Barleycorn	Yes	No	No	No

As nouns, John Barleycorn is a hypernym of vodka; that is, John Barleycorn is a word with a broader meaning than vodka:

vodka: unaged colorless liquor originating in Russia
John Barleycorn: an alcoholic beverage that is distilled rather than fermented

Other hypernyms of vodka include booze, hard drink, hard liquor, liquor, spirits, strong drink.

vodka (noun)	John Barleycorn (noun)
unaged colorless liquor originating in Russia	an alcoholic beverage that is distilled rather than fermented